Friday, March 8, 2019

Entomologists get excited over the strangest things. This morning I got my first bat bug sample ever, and I'm still all aflutter.

The pronotal fringe hairs on these common bed bugs (see arrow) are short, no longer than the width of the bed bug's eye. This feature is visible with a hand-lens even through a plastic zip-loc bag, as inthis photo. Image by Mike Merchant.

Bat bugs and swallow bugs are relatives of the common bed bug, Cimex lectularius--the species you are most likely to encounter on a daily basis in the pest control business. There are approximately 100 species in the bed bug family, referred to as cimicids (sigh MISS ids). Most are specialists on certain types of birds and bats. Generally, these bird and bat feeders have little interest in human blood, and cannot survive without their normal winged hosts.

Most of these other species of cimicid bugs look much like our common bed bug. They will be flat, oval-shaped and reddish-brown, with adult forms about the size of an apple seed.

Current thinking among biologists is that cimicids that specialize in birds and people are spin-offs from ancestral, bat-loving bed bugs. The data suggest that the switch-over from bat feeding to human feeding may not have been that long ago in evolutionary time. It's not difficult to imagine our ancient ancestors scratching from the first hungry bat bugs checking out other food choices in dark caves.

Today, it's rare to find our common bed bug feeding on bats, though it seems this species is less choosy about hosts than most other cimicids. Cimex lectularius has been found feeding on chickens, pigeons, swallows and even pets (though its clearly preferred host seems to be humans).

Distinguishing common bed bugs

Though bed bug identification is definitely a job for specialists, fortunately it's not difficult for any PMP to tell the difference between bat bugs and the common bed bug with a hand lens or office microscope. It has to do with the haircut.

Common bed bugs, our main human bed bug pest, have a fringe of short hairs on the edges of the pronotum, that "shield-like" plate behind the head (see first picture).

The pronotal fringe hairs of bat bugs and most bird bugs (see arrow) are longer than the eye iswide. Image of an eastern bat bug, Cimex adjunctus, by Mike Merchant.

Bat and swallow bug fringe hairs are longer (see lower picture). This shouldn't be hard to remember if you think of bats as being hairier than people. Though this character won't necessarily help you tell a bat bug from a swallow bug or pigeon bug, it is a reliable way to tell one of these non-people feeders from the common bed bug.

Don't walk away

Just because your customer has bat bugs instead of bed bugs, it doesn't mean your job is done. While treating bedrooms with a conventional bed bug treatment is unnecessary (bat bugs do not aggregate around beds, nor reproduce on people), there is still pest control to be done. Bat and bird bugs are best controlled by eliminating their preferred hosts from the structure and possibly treating the roosting/nesting sites for bed bugs.

Host elimination is not as simple as closing entry points for bats or birds. Most birds and all bats are federally protected and cannot be killed, nor active nests destroyed. Instead, they must be excluded at the end of nesting season. If you have questions about bird and bat exclusion, it's best to check with your state wildlife department. Nesting season for protected birds and bats varies from one area to another.

Unlike common bed bugs, it's unlikely that bat bugs and the various bird bugs will exhibit high levels of insecticide resistance. Any of the pyrethroid or pyrethroid-combination insecticides for common bed bugs should provide good control of bat and bird bugs around suspected harborages and entry points into living areas.

Bat bug and swallow bugs are not that common in our business. The sample I received today was, I learned later, collected from a home in Indiana. But if bed bugs are being found in unusual places, especially away from bedrooms, keep in mind that other bed bug species are out there. Remember that pest identification is always the starting point for good pest control. And it can be fun too; ask any entomologist.

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About Me

I have served as entomology specialist for Texas AgriLife Extension since 1989. I get to work with, and for, a bunch of great people including pest management professionals, school facilities managers, extension volunteers, researchers and other extension professionals. My areas of specialty center on research on insects affecting man including spiders, scorpions, fire ants, termites and others. My program also focuses on training school maintenance professionals in principles of integrated pest management (IPM). Our goal is to make schools healthier, cleaner places to study and live.